Does temperature matter?

It makes no difference to your body whether you sip cold or warm beverages — both are equally well absorbed. In one study, scientists at the Federal University of Minas Gerais, in Brazil, gave cold, warm, and hot water to athletes before and during a strenuous workout. They found the temperature of the water had no effect on the subjects’ endurance or hydration levels.

But don’t use hot water straight from the tap, as it pulls more lead from pipes than cold does. And let the water run for at least 60 seconds, Steven Patch, Ph.D., an authority on drinking-water safety and the director of the Environmental Quality Institute at the University of North Carolina in Asheville, advises — lead levels are highest in water that’s been sitting in pipes.

Can water go bad?

Yes. Or, rather, things in it can. “Water is a great medium for bacteria,” Kristin Reimers, a registered dietitian and the associate director of the Center for Human Nutrition, in Omaha, says. So think twice about sipping from that half-drunk water bottle that’s been sitting on your nightstand since the day before yesterday. A study in the Canadian Journal of Public Health in 2002 found high levels of bacteria (in nearly two-thirds of cases, high enough to exceed safety limits) in water bottles that were reused without being sterilized. Wash your bottle in hot, soapy water or in a dishwasher, or buy a bottle meant for constant use that’s sturdy and easy to clean. Place bottled water in a cool, dark place, since heat and light can damage the containers. Treated and stored appropriately, water can do the job it’s designed for: keeping your body healthy.

For more information on water, see:
Five Ways to Improve Your Drinking Water
Bottled Water Taste Test